feat: Add plan conversion statistics to extended explain info #2412

andygrove · 2025-09-17T15:23:17Z

Which issue does this PR close?

N/A

Rationale for this change

I would like to make it easier to see what % of operators are accelerated by Comet.

What changes are included in this PR?

Add some basic statistics to the "extended explain" output to show % of operators accelerated by Comet.

Example output:

BroadcastHashJoin
:- ColumnarToRow
:  +-  Scan parquet  [COMET: Dynamic Partition Pruning is not supported]
:        +- SubqueryBroadcast
:           +- ReusedExchange
+- BroadcastExchange
   +- CometColumnarToRow
      +- CometFilter
         +- CometScan [native_iceberg_compat] parquet 

Comet accelerated 33% of eligible operators (sparkOperators=4, cometOperators=2, transitions=2, wrappers=1).

How are these changes tested?

Manually

codecov-commenter · 2025-09-17T15:46:33Z

Codecov Report

❌ Patch coverage is 71.79487% with 11 lines in your changes missing coverage. Please review.
✅ Project coverage is 58.54%. Comparing base (f09f8af) to head (6436574).
⚠️ Report is 567 commits behind head on main.

Files with missing lines	Patch %	Lines
...n/scala/org/apache/comet/ExtendedExplainInfo.scala	71.05%	6 Missing and 5 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #2412      +/-   ##
============================================
+ Coverage     56.12%   58.54%   +2.41%     
- Complexity      976     1445     +469     
============================================
  Files           119      146      +27     
  Lines         11743    13534    +1791     
  Branches       2251     2356     +105     
============================================
+ Hits           6591     7923    +1332     
- Misses         4012     4379     +367     
- Partials       1140     1232      +92

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andygrove · 2025-09-17T16:58:10Z

Subset of output from benchmarks

Reading query 16 using path /mnt/bigdata/tpch/queries//q16.sql
Comet accelerated 87% of eligible operators (sparkOperators=1, cometOperators=7, transitions=0, wrappers=0).
Comet accelerated 84% of eligible operators (sparkOperators=4, cometOperators=22, transitions=0, wrappers=0).
Comet accelerated 80% of eligible operators (sparkOperators=4, cometOperators=17, transitions=0, wrappers=0).
Comet accelerated 75% of eligible operators (sparkOperators=1, cometOperators=3, transitions=0, wrappers=0).
Comet accelerated 100% of eligible operators (sparkOperators=0, cometOperators=3, transitions=0, wrappers=0).
Comet accelerated 84% of eligible operators (sparkOperators=4, cometOperators=22, transitions=1, wrappers=0).
Comet accelerated 84% of eligible operators (sparkOperators=4, cometOperators=22, transitions=1, wrappers=0).
Comet accelerated 75% of eligible operators (sparkOperators=2, cometOperators=6, transitions=1, wrappers=0).

andygrove · 2025-09-17T17:19:07Z

docs/source/user-guide/latest/installation.md

+    --conf spark.comet.explain.enabled=true \
    --conf spark.memory.offHeap.enabled=true \
-    --conf spark.memory.offHeap.size=16g
+    --conf spark.memory.offHeap.size=2g


Unrelated change, but we don't need 16g for this simple example

comphead · 2025-09-17T23:03:15Z

spark/src/test/scala/org/apache/comet/exec/CometExecSuite.scala

+
+          withSQLConf(CometConf.COMET_EXPLAIN_VERBOSE_ENABLED.key -> "true") {
+            val extendedExplain = new ExtendedExplainInfo().generateExtendedInfo(cometPlan)
+            assert(extendedExplain.contains("Comet accelerated 33% of eligible operators"))


would be this number fluctuating?

It is currently stable across all Spark versions that we test with.

I was wrong. There is a failure due to a different percentage. I will make the test less specific.

- DPP fallback *** FAILED *** (1 second, 553 milliseconds) "BroadcastHashJoin :- ColumnarToRow : +- Scan parquet [COMET: Dynamic Partition Pruning is not supported] : +- SubqueryBroadcast : +- BroadcastExchange : +- CometColumnarToRow : +- CometFilter : +- CometScan [native_iceberg_compat] parquet +- BroadcastExchange +- CometColumnarToRow +- CometFilter +- CometScan [native_iceberg_compat] parquet Comet accelerated 4 out of 9 eligible operators (44%). Final plan contains 3 transitions between Spark and Comet." did not contain "Comet accelerated 33% of eligible operators" (CometExecSuite.scala:124)

spark/src/main/scala/org/apache/comet/ExtendedExplainInfo.scala

comphead · 2025-09-17T23:46:58Z

Comet accelerated 33% of eligible operators (sparkOperators=4, cometOperators=2, transitions=2, wrappers=1).

From the user perspective it might be not very clear what is accelerated?
When seeing message first time, I thought all of them are accelerated?

 (sparkOperators=4, cometOperators=2, transitions=2, wrappers=1).

which is not the case?

andygrove · 2025-09-18T20:03:26Z

Comet accelerated 33% of eligible operators (sparkOperators=4, cometOperators=2, transitions=2, wrappers=1).
From the user perspective it might be not very clear what is accelerated? When seeing message first time, I thought all of them are accelerated?
 (sparkOperators=4, cometOperators=2, transitions=2, wrappers=1).
which is not the case?

Thanks, I will add documentation as part of this PR

parthchandra · 2025-09-18T22:14:54Z

spark/src/main/scala/org/apache/comet/ExtendedExplainInfo.scala

+  var transitions: Int = 0
+
+  override def toString: String = {
+    s"sparkOperators=$sparkOperators, cometOperators=$cometOperators, " +


Perhaps we could use a more verbose string here so that the meaning of these stats is a little more obvious

parthchandra · 2025-09-18T22:20:24Z

We could potentially add a method to get the plan stats independent of the explain string too. I can see this being useful in writing some tool to analyse queries/plans without executing them.

andygrove · 2025-09-29T19:56:47Z

Thanks for the reviews @comphead and @parthchandra. Could you take another look?

spark/src/main/scala/org/apache/comet/ExtendedExplainInfo.scala

parthchandra

lgtm. Minor improvement suggested. Also, is the comment re the unit test addressed?

Co-authored-by: Parth Chandra <[email protected]>

andygrove · 2025-10-01T15:48:37Z

Thanks for the reviews @parthchandra @comphead. I have addressed feedback and plan on merging this later today, unless you have any other feedback

…#2412)

andygrove added 5 commits September 17, 2025 08:25

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andygrove marked this pull request as ready for review September 17, 2025 18:12

andygrove requested review from kazuyukitanimura and parthchandra September 17, 2025 18:12

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andygrove and others added 3 commits September 30, 2025 08:23

Update spark/src/main/scala/org/apache/comet/ExtendedExplainInfo.scala

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Co-authored-by: Parth Chandra <[email protected]>

Refactor

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andygrove merged commit ca2e611 into apache:main Oct 1, 2025
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andygrove deleted the extended-explain-stats branch October 1, 2025 20:10

coderfender pushed a commit to coderfender/datafusion-comet that referenced this pull request Dec 13, 2025

feat: Add plan conversion statistics to extended explain info (apache…

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…#2412)

feat: Add plan conversion statistics to extended explain info #2412

feat: Add plan conversion statistics to extended explain info #2412

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